1. Field of the Invention
The present invention relates to a coupling between a toolholder and a toolholder support member used for metal working operations. In particular, the invention is directed to a coolant coupling between these two parts suitable for high pressure applications.
2. Description of Related Art
FIGS. 1-3 illustrate prior art and show a toolholder 10 for mounting within a clamping unit or toolholder support member 15. The toolholder 10 is made up of a body 12 having a front end 20 for holding a cutting tool such as a cutting insert 25. Although the toolholder 10 shown in FIGS. 1-3 is typical of a toolholder 10 used for non-rotating tooling, such as a lathe, it should be understood that the toolholder 10 may have attached to it any of a variety of tools that may be associated with either non-rotating or rotating applications.
The toolholder body 12 also has a back end 30 for supporting the body 12 within the toolholder support member 15. The back end 30 has a forwardly facing shoulder 32 and a tubular shank 35 which may be frusto-conical extending therefrom. The shank 35 is hollow, thereby defining a shank cavity 37 and the shank has a shank wall 40 with an exterior 42 and with radially extending perforations 45 having angled forwardly facing surfaces 50 adapted to be engaged by radially displaced balls 55 associated with the toolholder support member 15.
The toolholder support member 15 has a rearwardly facing surface 60 and a bore 65 extending forwardly therefrom.
Directing attention to FIG. 4, the bore 65 is sized such that adjacent to the rearwardly facing surface 60 is a first resilient interference fit segment 67 and spaced longitudinally therefrom is a separate second resilient interference fit segment 69. That feature of FIG. 4 is prior art. Returning to FIG. 2, the first resilient interference fit segment 67 occurs in a region where the toolholder shank 35 is comprised of a continuous band of material about the circumference of the shank 35, while the separate second resilient interference fit segment 69 occurs in a region where the radially displaced balls 55 act upon the angled forwardly facing surfaces 50 of the shank 35 to force the shank wall 40 against the bore wall 66 of the toolholder support member 15.
Directing attention to FIGS. 1 and 2, in operation, the lock rod 70 reciprocates along a longitudinal axis 72. As illustrated in FIG. 1, the lock rod includes depressions 74 and ramps 76 in the uncoupled state. As illustrated in FIG. 1, the locking balls 55 are recessed within the depression 74 of the lock rod 70 and the shank 35 is free to move back and forth within the bore 65. When the lock rod 70 is moved to the right (FIG. 2), the locking balls 65 are radially displaced from the depressions 74 and move outwardly along the ramp 76 to engage the angled forwardly facing surfaces 50 of the perforations 45 of the shank 35. By doing so, the toolholder 10 is drawn into the toolholder support member 15 to provide a resilient interference fit between the shank 35 and the bore 65, while at the same time, the forwardly facing shoulder 32 abuts with the rearwardly facing surface of the toolholder support member 15. The shank 35 may include a slot to radially orient the toolholder shank 35 within the toolholder support member 15.
Additional details of the toolholder 10 and the toolholder support member 15 and their relationship may be found in U.S. Pat. No. 4,723,877 and U.S. Pat. No. 4,747,735, each of which are assigned to Kennametal Inc., the assignee of the present application, and each of which is hereby incorporated by reference.
The toolholder 10 and toolholder support member 15 are made of high strength alloy steel.
Typically, during a metal working operation, a liquid coolant is introduced at the interface between the cutting tool, for example, cutting insert 25, and the workpiece to not only cool the interface but additionally to assist in removing material from this interface. In the past, for the arrangement illustrated in FIGS. 1 and 2, coolant was introduced through a passageway extending through the lock rod 70 and into the shank cavity 37 at which point a coolant passageway extended through the front end 20 of the toolholder 10 and was directed as desired. As cutting applications and materials became more sophisticated, there was a need to increase the pressure of the coolant and there now exists a need to provide coolant at very high pressures. In the prior art embodiments, the coolant was sealed within the toolholder 10 and the toolholder support member 15 through the use of rubber seals strategically located. However, such seals are less effective with high pressure coolant and, therefore, another design was required to accommodate high pressure coolant.